Limit Evaluations
1. The user provided several limit expressions and functions to analyze.
2. Let's clarify and solve each limit step-by-step.
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**Problem 1:** Evaluate $$\lim_{x \to 3} \frac{3 - \sqrt{5x + 4}}{\sqrt{x + 3} - 2}$$
Step 1: Substitute $x=3$ directly:
$$3 - \sqrt{5(3) + 4} = 3 - \sqrt{15 + 4} = 3 - \sqrt{19}$$
$$\sqrt{3 + 3} - 2 = \sqrt{6} - 2$$
Since direct substitution does not give $0/0$, compute the value:
$$\frac{3 - \sqrt{19}}{\sqrt{6} - 2}$$
Step 2: Rationalize the denominator:
$$\frac{3 - \sqrt{19}}{\sqrt{6} - 2} \times \frac{\sqrt{6} + 2}{\sqrt{6} + 2} = \frac{(3 - \sqrt{19})(\sqrt{6} + 2)}{6 - 4} = \frac{(3 - \sqrt{19})(\sqrt{6} + 2)}{2}$$
Step 3: Expand numerator:
$$3\sqrt{6} + 6 - \sqrt{19}\sqrt{6} - 2\sqrt{19}$$
Final limit:
$$\frac{3\sqrt{6} + 6 - \sqrt{114} - 2\sqrt{19}}{2}$$
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**Problem 2:** Evaluate $$\lim_{x \to 5} \frac{x - x - \sqrt{x + 1}}{\lim_{x \to 1} \frac{-x + 1 - \sqrt{x + 1} + 3}{x - 1}}$$
This expression is ambiguous; assuming the inner limit is:
$$\lim_{x \to 1} \frac{-x + 1 - \sqrt{x + 1} + 3}{x - 1}$$
Step 1: Simplify numerator:
$$-x + 1 - \sqrt{x + 1} + 3 = 4 - x - \sqrt{x + 1}$$
Step 2: Evaluate the limit as $x \to 1$:
Direct substitution gives numerator:
$$4 - 1 - \sqrt{2} = 3 - \sqrt{2}$$
Denominator:
$$1 - 1 = 0$$
Since denominator is zero, check if numerator also tends to zero:
At $x=1$, numerator is $3 - \sqrt{2} \neq 0$, so limit tends to infinity or does not exist.
Therefore, the entire expression is undefined or infinite.
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**Problem 3:** Evaluate $$\lim_{x \to 1} \frac{x - \sqrt{x + 4} - 2}{1/x - 2x + 1}$$
Step 1: Substitute $x=1$:
Numerator:
$$1 - \sqrt{1 + 4} - 2 = 1 - \sqrt{5} - 2 = -1 - \sqrt{5}$$
Denominator:
$$1/1 - 2(1) + 1 = 1 - 2 + 1 = 0$$
Since denominator is zero and numerator is not zero, limit tends to infinity or does not exist.
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**Problem 4:** Given function $$g(x) = 2x - \sqrt{x^2 + 2}$$
Evaluate $g(x)$ for given $x$ or analyze behavior.
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**Problem 5:** Evaluate $$\lim_{x \to 0} [f(x) + 3x]$$ where $f(x)$ is not explicitly given.
Cannot evaluate without $f(x)$ definition.
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**Summary:**
- Problem 1 limit evaluated with rationalization.
- Problems 2 and 3 limits tend to infinity or undefined.
- Problem 4 function given.
- Problem 5 insufficient data.
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"slug": "limit evaluations",
"subject": "calculus",
"desmos": {"latex": "y=2x - \sqrt{x^2 + 2}", "features": {"intercepts": true, "extrema": true}},
"q_count": 3
Final answer for Problem 1:
$$\lim_{x \to 3} \frac{3 - \sqrt{5x + 4}}{\sqrt{x + 3} - 2} = \frac{3\sqrt{6} + 6 - \sqrt{114} - 2\sqrt{19}}{2}$$